U.S. patent number 5,252,141 [Application Number 07/837,876] was granted by the patent office on 1993-10-12 for modular solar cell with protective member.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Yuji Inoue, Hiroshi Yamamoto.
United States Patent |
5,252,141 |
Inoue , et al. |
October 12, 1993 |
**Please see images for:
( Certificate of Correction ) ** |
Modular solar cell with protective member
Abstract
A solar cell module including at least one photovoltaic device,
covering material for covering the at least one photovoltaic
device, and a frame for covering the end portions of the covering
materials. The covering materials are provided, in the end portions
thereof, with a recess or a penetrating hole. The frame is provided
with a projection adapted to engage with the recess or penetrating
hole.
Inventors: |
Inoue; Yuji (Nagahama,
JP), Yamamoto; Hiroshi (Nagahama, JP) |
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JP)
|
Family
ID: |
26385595 |
Appl.
No.: |
07/837,876 |
Filed: |
February 20, 1992 |
Foreign Application Priority Data
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Feb 20, 1991 [JP] |
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3-045584 |
May 16, 1991 [JP] |
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3-139476 |
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Current U.S.
Class: |
136/251; 136/259;
136/291 |
Current CPC
Class: |
B32B
17/02 (20130101); H01L 31/048 (20130101); Y10S
136/291 (20130101); Y02E 10/50 (20130101) |
Current International
Class: |
H01L
31/048 (20060101); H01L 031/048 () |
Field of
Search: |
;136/251,259,291
;52/173R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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3235493 |
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Mar 1984 |
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DE |
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3513910 |
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Oct 1986 |
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DE |
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8329884 |
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Dec 1987 |
|
DE |
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59-125671 |
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Jul 1984 |
|
JP |
|
60-7761 |
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Jan 1985 |
|
JP |
|
60-214550 |
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Oct 1985 |
|
JP |
|
61-090472 |
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Dec 1986 |
|
JP |
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62-87461 |
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Jun 1987 |
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JP |
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62-87462 |
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Jun 1987 |
|
JP |
|
62-20123 |
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Aug 1987 |
|
JP |
|
2-21670 |
|
Jan 1990 |
|
JP |
|
2-47065 |
|
Mar 1990 |
|
JP |
|
Other References
"Photovoltaic Roofs" by Robert W. Drummond et al. NTIS Tech Notes;
No. 1C, Jan. 1985, Springfield, Va., US.; p. 79..
|
Primary Examiner: Weisstuch; Aaron
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper &
Scinto
Claims
We claim:
1. A solar cell module comprising at least one photovoltaic device,
covering material for covering said at least one photovoltaic
device, and a frame for covering the end portions of said covering
materials;
wherein said covering materials are provided, in the end portions
thereof, with a recess or a penetrating hole, and said frame is
provided with a projection adapted to engage with said recess or
penetrating hole.
2. A solar cell module according to claim 1, wherein said
projection is composed of an engaging member which passes through a
penetrating hole provided in said frame and engages with said
penetrating hole of the end portions of said covering
materials.
3. A solar cell module according to claim 2, wherein said engaging
member has an external diameter "a" equal to or larger than 5 mm in
an externally exposed portion, and has a ratio a/b of said external
diameter to a shaft diameter "b" in said penetrating hole equal to
or larger than 1.2.
4. A solar cell module according to claim 2, wherein said engaging
member is composed of an eyelet having a penetrating hole in the
center.
5. A solar cell module according to claim 1, wherein said frame
projection is provided integrally with a groove for accommodating
the end portions of said covering materials, and the width of said
groove is, at least in part, smaller than the thickness of the end
portions of said covering materials.
6. A solar cell module according to claim 1, wherein said frame
projection is provided integrally with a groove and said projection
is provided in plural number in mutually opposed relationship in
the groove.
7. A solar cell module according to claim 1, wherein a thickness of
each end portion of said covering materials is less than a
thickness of a portion of the solar cell wherein the covering
materials sandwich said at least one photovoltaic device, and a
thickness of the recess or penetrating hole of each end portion of
the covering materials engaging with said projections is less than
the thickness of the remainder of the end portion.
8. A solar cell module according to claim 1, wherein said at least
one photovoltaic device includes a non-monocrystalline
semiconductor layer.
9. A solar cell module according to claim 1, wherein said at least
one photovoltaic device includes an amorphous silicon layer.
10. A solar cell module according to claim 1, comprising a
plurality of said photovoltaic devices, which are serially
connected.
11. A solar cell module comprising:
a solar cell portion including at least one photovoltaic device,
and covering materials for covering said at least one photovoltaic
device;
a support member for supporting said at least one solar cell;
and
a protective member for protecting end portions of at least two
adjacent support members in an array of a plurality of said support
members;
wherein said support member is composed of a deformable
plate-shaped member, end portions of which are so folded as to form
grooves for accommodating the end portions of said covering
materials.
12. A solar cell module according to claim 11, wherein said grooves
are each provided with at least one projection adapted to engage
with a recess or penetrating hole provided in said covering
materials.
13. A solar cell module comprising:
a solar cell portion including at least one photovoltaic device,
and covering materials for covering said at least one photovoltaic
device;
a support member for supporting said at least one solar cell;
and
a protective member for protecting end portions of at least two
adjacent support members in an array of a plurality of said support
members;
wherein said support member is provided, at the end portions
thereof, with independent members so as to form grooves for
accommodating the end portions of said covering materials.
14. A solar cell module according to claim 13, wherein said grooves
are each provided with a projection adapted to engage with a recess
or a penetrating hole provided in said covering materials.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a solar cell adapted for use in
various electronic equipment or electric power supply devices, and
more particularly to a modular solar cell with an improved
protective member constituting protective means therefor.
2. Related Background Art
Because of the recent forecast for the warming of the entire earth
by the greenhouse effect resulting from the increase of atmospheric
CO.sub.2, the need has become stronger for clean energy production
without CO.sub.2 discharge. However, nuclear power generation,
which is free from CO.sub.2 discharge, is still associated with the
problem of disposal of radioactive products, so that clean energy
with improved safety is desired. Among the future candidates of
such clean energy, the solar cell is very desirable because of its
cleanness, safety, and easy handling.
Among various solar cells, those based on non-monocrystalline
semiconductors such as amorphous silicon or copper indium selenide
are the subjects of intensive developmental works, as these
materials can be prepared in a large area and with a low production
cost. If impact resistance or flexibility is required, such solar
cells are often formed on a metal substrate such as of stainless
steel.
For the purpose of reducing the weight of the solar cell formed on
the stainless steel substrate, ensuring flexibility, and providing
weather resistance and impact resistance, such solar cell is sealed
with a resin such as a fluorinated resin or ethylene vinyl acetate
(EVA). After such resin sealing, the end portions of the solar cell
are covered with a protective frame composed of a metal such as
aluminum or a polymer such as polyvinyl chloride or synthetic
rubber, for the purpose of protecting the end faces and providing a
support member. Particularly if flexibility is required for the
solar cell module, there is usually employed a flexible polymer
such as synthetic rubber of soft polyvinyl chloride.
The fixation between the end portions of the sealed solar cell and
the protective frame, for example of polymer material, is achieved
by an adhesive material, after the contact faces are pre-treated
with plasma, strong acid, or strong alkali for facilitating the
adhesion.
FIG. 1 is a schematic cross-sectional view of a conventional prior
art solar cell.
In FIG. 1 there are shown a solar cell device 401 formed on a
conductive substrate; a resinous covering material 404 for sealing
said solar cell device 401; a resin-sealed solar cell 402; and a
protective frame 403 composed of flexible resin. The outermost
layer of the resin 404 is usually composed of a fluorinated resin,
in consideration of weather resistance. Also the protective frame
403 is usually composed of synthetic rubber or soft polyvinyl
chloride, in consideration of the weather resistance and
flexibility.
Since the fluorinated resin, employed for sealing the solar cell
and the synthetic rubber or soft polyvinyl chloride constituting
the protective frame are difficult to adhere with, the adhesion
with the adhesive material is executed after the contact faces of
the resin 404 and the protective frame 403 are pretreated with
plasma, strong acid, or strong alkali, for facilitating the
adhesion.
Although the solar cells are sometimes use indoors under the light
of fluorescent lamps, those used outdoors are required to have
sufficient durability to the influence of various ambient
conditions such as high temperature, low temperature, high
humidity, rain, wind, etc. For this reason, the conventional solar
cell module is usually composed of a seal portion 4040 for the
solar cell device and a frame portion 403.
FIG. 2 is a schematic cross-sectional view of another conventional
prior art solar cell module.
In a laminate member 21 constituting the solar cell module, the
light-receiving face (upper face in the drawing) of a solar cell
device 22 is covered, via an adhesive material 23, by a sheet-like
surface protecting material 25 composed of transparent resin, while
the rear face (lower face) of the device 22 is covered, via an
adhesive material 23, by sheet-like rear face protecting material
25. Said coverings are provided by vacuum lamination, and the solar
cell device 22 is hermetically sealed inside. The laminate member
21 is cut at positions outside the solar cell device 22, and the
cut faces constitute the end faces 21c, 21d of said laminar member
21.
Aluminum frames 26, 27 for supporting the laminate member 21 are
respectively provided with grooves 26a, 27a, into which are
respectively inserted the edge portions 21a, 21b of the laminate
member 21. Fillers 26f, 27f, for example of silicone rubber are
provided in the gaps between the edges 21a, 21b and the grooves
26a, 27a, in order to prevent intrusion of water and vapor into the
interior of the laminate member 21.
The solar cell modules constructed as shown in FIGS. 1 and 2 are
positioned outdoors and used under various climatic conditions such
as high temperature, low temperature, high humidity, wind, rain,
etc.
However, the adhesive strength still is not sufficiently high even
with the above-mentioned pretreatment, and the frames 403, 26, 27
may be dismantled when a strong external force is applied.
Adequate reliability cannot be attained even when the adhesive
strength is increased by the above-mentioned pretreatment prior to
the adhesion, the frames 403, 26, 27 may be dislodged from the
solar cell module after prolonged outdoor use or by a strong
external force.
Such dislodging of frames leads to peeling of the covering material
of the solar cell from the end faces thereof, thus deteriorating
the quality of the solar cell.
Also the filler, for example of silicone rubber, filled in the gaps
between the frame grooves and the edge portions of the covering
material as in the solar cell module shown in FIG. 2, often does
not have a sufficiently low moisture permeability even though the
water absorbability is low. Besides, the complete filling of said
gaps with the filler is difficult, and said gaps eventually remain
incompletely filled. As a result, moisture enters the grooves in
the course of use of the solar cell and eventually reaches the
solar cell device through the cut end faces of the module, thereby
causing shortcircuiting of the solar cell device or destruction
thereof by peeling of the thin film thereof.
SUMMARY OF THE INVENTION
An object of the present invention is to resolve the
above-mentioned drawbacks and to provide a highly reliable solar
cell module which does not deteriorate after prolonged outdoor use
or under a strong external force.
Another object of the present invention is to provide a solar cell
module with an improved ability for preventing moisture intrusion
from the end faces of the module edges, inserted into the frame
grooves, into the interior of the module.
Still another object of the present invention is to provide a solar
cell provided with a photovoltaic device, covering materials
covering said device, and a frame member covering the end portion
of said covering materials, wherein said covering materials are
provided, in the end portion thereof, with recess(es) or
penetrating hole(s) while said frame is provided with projection(s)
engaging with said recess(es) or penetrating hole(s).
Still another object of the present invention is to provide a solar
cell module provided with:
a solar cell including a photovoltaic device, and a covering
material for covering said photovoltaic device;
a support member for supporting said solar cell; and
a protective member for protecting the end portions of at least two
adjacent support members in an array of plural support members;
wherein said support members are each composed of a plate-shaped
deformable member, the end portion of which being folded so as to
form a slit for accommodating the end portion of said covering
material.
Still another object of the present invention is to provide a solar
cell module provided with:
a solar cell including a photovoltaic device, and a covering
material for covering said photovoltaic device;
a support member for supporting said solar cell; and
a protective member for protecting the end portions of at least two
adjacent support members in an array of plural support members;
wherein said support members are each provided, at the end portion
thereof, with another member so as to form a slit for accommodating
the end portion of said covering material.
The solar cell module of the present invention, including a solar
cell sealed in a covering material and a protective frame for
protecting the end portion of said solar cell by compressing the
end portions thereof, is distinguished by said solar cell and said
protective frame being respectively provided with penetrating
holes, and being mutually fastened by engaging members penetrating
through said holes. Said engaging members preferably have an
external diameter a at least equal to 5 mm in a portion exposed
from the solar cell module, and a ratio a/b, to the shaft diameter
b in said penetrating hole, at least equal to 1.2.
More preferably, said engaging member is composed of an eyelet
having a penetrating hole in the center.
The present invention improves the strength by fastening the solar
cell and the protective frame therefor with an engaging member
passing through the penetrating hole, in comparison with the
conventional structure in which fastening relies solely on the
adhesive material. Strong fastening is achievable even with a
combination of materials difficult to adhere with an adhesive
material, such as a resin-sealed solar cell and a protective frame
composed of resin.
Fastening with a higher strength can be achieved by the use of an
engaging member, having an external diameter of at least 5 mm in a
portion exposed from said solar cell module and a ratio a/b to the
shaft diameter b in said penetrating hole at least equal to
1.2.
Also, said engaging member is preferably composed of an eyelet,
having a penetrating hole in the center, whereby said hole can be
utilized, for example, for passing a rope after the completion of
the solar cell module, and the fastening of said module can be
facilitated.
Also the foregoing objects can be attained, according to the
present invention, by a solar cell module which is provided, on the
internal faces of the frame grooves, with projections coming into
contact with the edge portion, other than end faces, of the
laminate member, wherein the width of said grooves corresponding to
the positions of said projections is smaller than the thickness of
the edge portion of said laminate member.
Because of said smaller width of the grooves, the edge portion
inserted into said grooves is locally pressed in the areas coming
into contact with said projections, whereby the moisture intruding
from the end faces of the edge portion of the laminate member into
the interior of said edge portion does not proceed further beyond
the thus pressed portions.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 2 are schematic cross-sectional views of conventional
solar cell modules;
FIG. 3 is a schematic cross-sectional view of a solar cell module
of the present invention;
FIGS. 4A and 4B are a schematic views of an engaging member shown
in FIG. 3;
FIG. 5 is a schematic perspective view cf a solar cell module of
the present invention;
FIG. 6 is a schematic cross-sectional view of a solar cell module
constituting another embodiment of the present invention;
FIG. 7 is a schematic plan view showing an example of the
photovoltaic device adapted for use in the present invention;
FIG. 8 is a cross-sectional view along a line 8--8' in FIG. 7;
FIG. 9 is an exploded view showing the structure of a covered solar
cell adapted for use in the present invention;
FIG. 10 is a schematic perspective view of a solar cell module of
the present invention;
FIG. 11 is a schematic perspective view of a frame adapted for use
in the present invention;
FIG. 12 is a schematic view showing an application of the solar
cell module of the present invention;
FIGS. 13, 14, 15A and 15B are schematic cross-sectional views of
solar cell modules constituting other embodiments of the present
invention;
FIG. 16 is a schematic perspective view of a support member adapted
for use in the present invention;
FIGS. 17 and 18 are schematic views of showing assembling steps of
the solar cell module of the present invention;
FIGS. 19, 20, 21A and 21B are schematic cross-sectional views of
solar cell modules constituting other embodiments of the present
invention;
FIG. 22 is a schematic perspective view of another example of
support member adapted for use in the present invention;
FIGS. 23 and 24 are schematic views showing assembling steps of the
solar cell module of the present invention;
FIGS. 25 and 26 are schematic cross-sectional views of solar cell
modules constituting other embodiments of the present
invention;
FIG. 27 is a schematic cross-sectional view of a photovoltaic
device adapted for use in the present invention; and
FIG. 28 is a schematic external perspective view of the solar cell
module of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following there will be given a detailed explanation of a
photovoltaic device employed as the solar cell in the present
invention.
FIG. 27 is a schematic cross-sectional view of the photovoltaic
device, in which a substrate 1301 with a conductive surface can be
composed, for example, of a conductive substrate such as stainless
steel, aluminum, copper or carbon sheet, or of a glass substrate or
a plastic sheet bearing thereon a transparent conductive film such
as of ITO (indium tin oxide), SnO.sub.2, In.sub.2 O.sub.3, or ZnO.
Although not illustrated, there may be further provided a
conductive surface layer, for example of Ti, Cr, Mo, W, Al, Ag, or
Ni.
On said substrate 1301 there is provided a bottom photovoltaic cell
consisting of an N-layer 1302, an I-layer 1303, and a P-layer 1304,
and further provided thereon is a top photovoltaic cell consisting
of an N-layer 1305, an I-layer 1306, and an N-layer 1307.
A transparent electrode 1308, employed in the solar cell of the
present invention, can be composed, for example, of In.sub.2
O.sub.3 SnO.sub.2, In.sub.2 O.sub.3 -SnO.sub.2, ZnO, TiO.sub.2,
Cd.sub.2% Sn.sub.4, or a crystalline semiconductor layer with a
high concentration of impurity doping, and can be formed for
example, by evaporation by resistance heating, electron beam
evaporation, sputtering, spraying, CVD, or impurity diffusion. Grid
electrodes 1309 are provided thereon.
The potting material for resin sealing of the solar cell device of
the present invention can be composed, for example, of
ethylene-vinyl acetate copolymer, polyvinylbutyrol, or silicone
resin, but other materials may also be employed for this
purpose.
The covering material for covering the solar device is required to
have a good light transmitting property and resistance against
ultraviolet light or ozone, and is composed, for example, of a
fluorinated resin film or silicone resin, but other materials may
also be employed for this purpose.
The protective frame, for compressing and protecting the end
portion of the solar cell module of the present invention, can be
composed, for example, of polyvinyl chloride or synthetic rubber in
consideration of weather and impact resistance. However, polyvinyl
chloride is preferred in consideration of weather resistance and
ease of molding, and soft polyvinyl chloride is particularly
preferred in order to provide the solar cell module with
flexibility. On the other hand, if mechanical strength is required,
a metallic material is preferred.
The material for the projection and engaging member to be employed
in the present invention is not particularly limited, but is
selected in consideration of weather resistance, impact resistance,
and resistance to seawater. For example, there may be employed a
metallic member such as an eyelet, rivet, or screw, or a
thermofusible resinous molded member of polypropylene, melamine
resin, or hard polyvinyl chloride. Among these, the eyelet is
preferred in consideration of safety, fastening strength, and cost.
On the other, if increased strength is required in combination with
simplicity of preparation, said member is preferably integrated
with the frame.
The semiconductor materials constituting the aforementioned N, I,
and P layers are preferably composed of amorphous, polycrystalline,
or microcrystalline materials. Specific examples of such materials
include semiconductors of the group IV of the periodic table, such
as silicon, germanium, silicon-germanium, and silicon carbide, and
compound semiconductors such as CuInSe.sub.2, CdS, GaAs, and
ZnSe.
The aforementioned layer of Ti, Cr, Mo, W. Al, Ag, or Ni can be
formed, for example, by evaporation by resistance heating, electron
beam evaporation, or sputtering.
The amorphous silicon constituting the PIN junction can be formed
by plasma CVD employing silane gas. The polycrystalline silicon
constituting a PN junction can be formed by sheet formation with
fused silicon, and the compound semiconductor junction such as
CuInSe.sub.2 /CdS can be formed by electron beam evaporation,
sputtering, or electrodeposition.
EXAMPLE 1
FIG. 3 is a schematic cross-sectional view of the solar cell module
of the present invention, wherein there are shown a solar cell
device 105 formed on a conductive substrate; a resinous covering
material 110 for sealing said solar cell device 105; a resin-sealed
solar cell module 101; a flexible resinous protective frame 102;
and an engaging member 104 for mechanically fastening together the
sealed solar cell module 101 and the protective frame 102.
FIG. 4 shows that the details of the engaging member 104 in a plan
view and a cross sectional view along a line 4--4'. Said member 104
of the present embodiment has a portion exposed from the solar cell
module with an external diameter a at least equal to 5 mm, and a
ratio a/b to the shaft diameter b in the penetrating hole at lease
equal to 1.2.
In the present embodiment, the protective frame 102 may be easily
dislodged from the engaging member 104 if the external diameter a
thereof is less than 5 mm, or if the ratio a/b is less than
1.2.
Said engaging member 104 preferably has an external diameter a at
lease equal to 5 mm, but it is more preferably at least equal to 7
mm. Also the ratio a/b of said diameter to the diameter of the
shaft passing through the penetrating hole is preferably at least
equal to 1.2, but said ratio is more preferably at least equal to
1.5.
Also, the end 105a of the solar cell device 105 is preferably
positioned inside the internal end 102a of the protective frame
102.
EXAMPLE 2
FIG. 5 is an external perspective view of the solar cell module of
the present example, and FIG. 6 is a cross-sectional view along a
line 6--6' in FIG. 5.
In FIGS. 5 and 6 there are shown resin 110 for sealing a solar cell
device 105; a resin-sealed solar cell module 101; a protective
frame 102; 103 serving as engaging members; and a lead wire
109.
In the following there will be given a detailed explanation of the
manufacturing steps and materials of the solar cell module of the
present example. Said module consists of a serial connection of
plural solar cell devices as shown in FIG. 7.
FIG. 7 is a schematic plan view of a solar cell device 200 before
serial connection, and FIG. 8 is a cross-sectional view showing the
laminar structure along a line 8--8' in FIG. 7.
In FIGS. 7 and 8 there are shown a stainless steel substrate 201;
an Al-Si layer 202; a non-monocrystalline silicon photoelectric
layer 203 with a PIN structure; an ITO layer 204; Ag electrodes
205; a tin-plated copper bus bar 206; a device isolation area 207;
adhesive silver ink 208; an exposed portion 209 of the stainless
steel substrate for making serial connection; and an insulating
tape 210 for preventing shortcircuiting.
The above-explained solar cell device was prepared by sputtering
Al, containing 1% Si to a thickness of 5000 .ANG. in a roll-to-roll
process on a washed and rolled stainless steel substrate 201, then
forming silicon layers 203 of N, I, and P types of a total
thickness of 4000 .ANG. by plasma CVD employing SiH.sub.4, B.sub.2
H.sub.6, and H.sub.2, and forming an ITO 204 layer of 800 .ANG.
thickness by resistance-heated evaporation.
Then current-collecting electrodes 205 for the ITO layer were
prepared by screen printing of silver paste. Then a bus bar
electrode 206 was placed perpendicularly to the silver electrodes,
and adhesive silver ink 208 was placed at the crossing points,
thereby connecting said silver electrodes 205 with the bus bar
electrode 206.
In this example, seven solar cell devices shown in FIG. 7 were
serially connected. The output voltage was 6 V.
Then the serially connected solar cell devices were sealed as shown
in FIG. 9. FIG. 10 schematically shows the solar cell after vacuum
lamination. In FIGS. 9 and 10 there are shown serially connected
solar cell devices 105; glass fiber layers 301 for limiting the
resin flow; ethylene vinyl acetate (EVA) resin layers 302;
fluorinated resin layers 303; and a lead wire 109 connected to the
solar cell.
The resin sealing was conducted by fusing the EVA resin at 140 C
with a vacuum laminator. The face of the fluorinated resin, to be
adhered to the EVA, was plasma treated in advance.
Then a protective frame 102, molded in a U shaped channel form with
soft polyvinyl chloride, as shown in FIG. 11, was mounted on the
end portion of the thus vacuum laminated solar cell. In this
operation, the mounted portion was temporarily adhered by silicone
adhesive.
Then holes for eyelets were opened in the solar cell and protective
frame 102, and twelve eyelets 103 with an external diameter of 7 mm
and a shaft diameter of 4 mm were installed as shown in FIG. 6.
The solar cell module of this example, prepared as explained above,
was subjected to a tensile test. In this test, the protective frame
102 was repeatedly given a tensile test. In this test, the
protective frame 102 was repeatedly given a tensile force of 5 kg
for 5 seconds, and the change in appearance of the solar cell
module was observed. The tensile force was applied 100 times, and
the obtained results are shown in Table 1.
REFERENCE EXAMPLE
The reference example employed the conventional structure shown in
FIG. 1. In this structure, the preparation was conducted in the
same manner as in example 1, until the vacuum lamination of the
solar device 401. Then the surface of fluorinated resin was plasma
treated only at the portions to be adhered to the protective frame
403 molded from soft polyvinyl chloride, and said frame 403 was
mounted on the end portions of the solar cell 402 as shown in FIG.
1. During said mounting silicone adhesive was coated on the
mounting portions, in order to adhere the solar cell 402 and the
protective frame 403. The obtained module was subjected to a
tensile test in the same manner as in example 1, and the obtained
results are shown in Table 1.
EXAMPLE 3
FIG. 12 is an external perspective view of example 3 of the present
invention, wherein there are shown a resin-sealed solar cell 101;
eyelets 106; strings 107 for fastening the solar cell module; a
protective frame 109; and a lead wire 109.
The solar cell module of the present invention is safe in use, as
it is flexible and without a rigid frame such as of metal. For this
reason, said solar cell module can be used on a yacht or in
camping. For these applications, holes are generally required for
passing strings therethrough for mounting.
In this example, the eyelets with penetrating holes for passing
said strings therethrough also serve as the engaging members for
fixing the protective frame provided at the end portion of the
solar cell.
The example shown in FIG. 12 was prepared in the same manner as
example 1, except for the size of the eyelets 106 and the form of
the protective frame 108 composed of polyvinyl chloride.
The eyelets 106 employed in this example had an external diameter
of 23 mm, a shaft diameter of 14 mm, and a height of 6 mm. Said
eyelets allow passage of the ropes ordinarily used on a yacht.
The form of the protective frame 108 composed of polyvinyl chloride
was varied according to the size of the eyelets 106.
The solar cell module of the present example was also subjected to
the tensile test explained above, and the obtained results are
shown in Table 1.
EXAMPLE 4
In this example, a solar cell module was prepared in the same
structure and by the same process as in Example 1 shown in FIGS. 5
and 6, except that the external diameter of the eyelets was
selected as 3 or 5 mm and the ratio a/b of the external a to the
shaft diameter b was selected as 1.8, and was subjected to a
tensile test in a similar manner. The obtained results are shown in
Table 1.
EXAMPLE 5
In this example, a solar cell module was prepared and tensile
tested in the same manner as in the example 1 shown in FIGS. 5 and
6, except that the external diameter of the eyelets was set at 7 mm
and the ratio a/b of the external diameter a to the shaft diameter
b of the eyelets was varied in the range of 1.0-1.8. The obtained
results are shown in Table 1.
Table 1 shows the results obtained in the examples 1-4 and in the
reference example. Five samples A-E were prepared under the same
conditions described in each of said examples and reference
example, but the quality showed certain fluctuations because of
manual preparation of the samples.
Table 1 shows the number of repeated applications of tensile force
required until the protective frame was dislodged from the solar
cell module. In the Examples 1 and 2, the protective frame was not
dislodged from the module after 100 cycles of tensile force.
On the other hand, in the reference example, the dislodging of the
protective frame took place within 10 cycles in all five samples.
This result proved that the present invention significantly
improved the performance of the solar cell module.
Also, the results of the Example 3 indicate that the eyelets are
particularly effective when the external diameter a is equal to or
larger than 5 mm.
Also, the results of Example 4 indicate that the eyelets are
particularly effective when the ratio a/b of the external diameter
a to the shaft diameter b is equal to or larger than 1.2.
As will be apparent from the foregoing, the solar cell modules of
the Examples 1-5, in which the resin-sealed solar cell and the
resinous protective frame are fixed by engaging members passing
through the penetrating holes provided in these components, are
characterized by excellent reliability, long service life; and
increased flexibility, as they are free from dislodging of the
protective frame even under an external force.
Also, secure mechanical strength can be obtained by the use of
engaging members which have an external diameter at least equal to
5 mm in portions exposed from the solar cell module and a ratio of
said external diameter to the diameter of a shaft portion passing
through the penetrating holes, equal to or larger than 1.2.
Also, the engaging member can be composed of an eyelet having a
penetrating hole therein, whereby said hole can be used for passing
strings or support members for fastening or mounting the solar cell
module thereby fixing the module. It is therefore rendered possible
to simplify the steps of manufacture, and to increase the ratio of
the photoelectric conversion area within the solar cell module,
thus improving the conversion efficiency per unit area.
TABLE 1
__________________________________________________________________________
Number of cycles of repeated tensile force application until
dislodging of protective frame from solar cell module. "No change"
indicates absence of dislodging after 100 cycles. Example 3 Example
4 Example 1 Ref. ex. Example 2 a = 3 mm a = 5 mm a/b = 1.0 a/b =
1.2 a/b = 1.5 a/b = 1.8
__________________________________________________________________________
A no change 4 no change 10 no change 7 no change no change no
change B no change 2 no change 8 65 12 48 no change no change C no
change 1 no change 8 81 4 94 no change no change D no change 1 no
change 15 no change -- -- -- -- E no change 1 no change 12 no
change -- -- -- --
__________________________________________________________________________
EXAMPLE 6
FIG. 13 is a schematic cross-sectional view of the principal
portion of a solar cell module constituting a example of the
present invention.
In a laminate member 1 constituting a solar cell module, the
light-receiving face (upper face in the drawing) of a solar cell
device 2 composed, for example of amorphous silicon, is covered,
via an adhesive material 3, by a sheet-like surface protecting
material composed of transparent resin, and the bottom (lower) face
is also covered, via an adhesive material 3, by a sheet-like bottom
face protecting material 5. Said coverings are provided by vacuum
lamination, whereby the solar cell device 2 is hermetically sealed
inside the laminate member 1. Said laminate member 12 is cut, for
example, in a rectangular form at positions outside the solar cell
device 2, and the cut faces constitute the end faces 1c, 1d of the
laminate member 1. The wirings and output terminals of the solar
cell device 2 are not illustrated, but said output terminals are
withdrawn from suitable positions on the end faces of the laminate
member 1.
Frames 6, 7, for example of aluminum, for supporting the laminate
member 1, have an identical structure. Therefore, the following
explanation will be concentrated on the frame 6 illustrated at the
right-hand side.
The frame 6 is provided with a slit-shaped groove 6a extending
perpendicularly to the plane of drawing, and, on the mutually
opposed internal faces 6b, 6c of said groove 6a, there are
respectively provided projections 6d, 6e which are in mutually
opposed positions and extend continuously from an end of the groove
6a to the other. The width of the groove 6a, or the distance
between the internal faces 6b and 6c, is larger than the thickness
of the edge portion 1a of the laminate member 1, while the distance
between the peaks of the projections 6d and 6e is smaller than said
thickness. In a gap between the groove 6a and the edge portion 1a
inserted therein beyond the projections 6c, 6d, there is a filler
material 6f composed, for example, of silicone rubber.
Within the edge portion 1a, the surface protecting member 4 and the
rear face protecting member 5, coming into contact with the
projections 6d, 6e, are locally pressed and distorted by said
projections, and the adhesive material 3 sandwiched between said
protecting members is also pressed. As a result, moisture entering
from the end face 1c of the laminate member 1 into the interior of
the edge portion la cannot intrude the interior beyond said pressed
portion.
The projections 6d, 6e are preferably formed without pointed ends,
for example, spherically, in order to facilitate the insertion of
the edge portion 1a and in order not to damage the surface
protecting material 4 and the rear face protecting material 5 even
after prolonged pressing thereon. Said projections 6d, 6e need not
necessarily be continuous from an end of the groove 6a to the
other, but may be intermittently provided. Said projections 6d, 6e
may be formed as separate members and mounted on the frame 6. The
material of the projections 6d, 6e and/or the frame 6 is not
limited to aluminum but can be any other material as long as it can
facilitate the insertion of edge portion 1a and can press the edge
portion 1a with a constant pressure over a prolonged period.
EXAMPLE 7
FIG. 14 is a schematic cross-sectional view of the principal part
of a solar cell module, constituting a seventh example of the
present invention.
The structure of this example is the same as that of example 6,
except that the grooves 16a, 17a of the frames 16, 17 are
respectively provided with projections 16d, 17d only on one
internal face 16b, 17b of each groove. In FIG. 14, components
equivalent to those in FIG. 13 are represented by the same symbols
added by 10.
In the following, there will be explained an experiment of placing
the solar cell modules of the present invention and the
conventional solar cell modules under high humidity and measuring
the shortcircuiting of the solar cell devices resulting from
moisture intrusion.
EXAMPLE 8
A solar cell device was prepared by laminating, on a stainless
steel substrate, amorphous silicon films of N, I, P, N, I, and P
types in succession by RF glow discharge, then vacuum evaporating
an ITO film as the transparent electrode, and finally printing
silver paste as the grid electrodes. Thirteen units of such device,
each 30.times.9 cm, were serially connected.
Said stainless steel substrate was composed of SU430 of a thickness
of 0.2 mm, the surface of which was annealed at ca. 1100.degree. C.
in ammonia gas.
The above-mentioned lamination of amorphous silicon films was
conducted in the following manner. A raw material gas, for example
for an N-type amorphous silicon film, was introduced into a
discharge zone in a vacuum chamber in which the substrate was
placed in advance, and the discharge was induced by controlling the
pressure in the chamber at about 2 Torr and supplying the
electrodes of the discharge zone with high-frequency electric
power, thereby decomposing said gas and depositing an N-type
amorphous silicon film on the substrate. Amorphous silicon films of
N, I, P, N, I, and P types were deposited in succession on the
substrate, by repeating the above-explained procedure. The raw
material gases for the amorphous silicon film were Si.sub.2
H.sub.6, H.sub.2,a nd PH.sub.3 for the N-type; Si.sub.2 H.sub.6 and
H.sub.2 for the I type; and SiH.sub.4, H.sub.2 and Bf.sub.3 for the
P-type. The substrate temperature during the deposition of said
film was 350.degree. C. for the N- and I-types, and 300.degree. C.
for the P-type.
The vacuum evaporation of said transparent electrode was conducted
in the following manner, employing a 50-50 alloy of indium and
tin.
Oxygen gas was introduced at a pressure of ca. 0.003 Torr into a
chamber in which the substrate with laminated amorphous silicon
films and a crucible filled with said alloy were placed in advance,
and a current was supplied to a tungsten wire wound around said
crucible to fuse said alloy, thereby depositing indium tin oxide
onto the surface of the amorphous silicon films laminated on the
substrate. The substrate temperature was controlled at 225.degree.
C. The material of the transparent electrode is not limited to the
indium tin oxide employed in this example, but may be composed of
other materials, such as indium oxide. The transparent electrode
may also be formed by sputtering, instead of vacuum
evaporation.
In the following, there will be described the laminate member 1
containing therein the solar cell device 2 thus prepared. The
adhesive 3 was composed of sheet-like EVA (ethylene-vinyl acetate
copolymer) which was relatively easily thermosettable. The surface
protecting material 4 was composed of Tefzel (trade name of DuPont
de Nemours, Inc.), a sheet-like transparent fluorinated resin with
a thickness of 100 .mu.m. The rear face protecting member 5 was
composed of a Tedlar (trade name of DuPont de Nemours) which is a
white fluorinated resin, different from the surface protecting
material and covered with aluminum foils on both sides. The rear
face protecting material 5, sheet-like adhesive 3, solar cell
device 2, sheet-like adhesive 3, and surface protecting material 4
were superposed in this order, subjected to vacuum lamination in a
vacuum laminator at ca. 150.degree. C., and cut at positions about
2 cm outside the periphery of the solar cell device 2, whereby the
laminate member 1 of rectangular shape was obtained. The cut end
faces 1c, 1d were not particularly treated.
In the following are described frames 6, 7. For each laminate
member 1, there were prepared four frames, each having a pair of
mutually opposed projections 6d, 6e, 7d, 7e as shown in example 6
and matching the thickness and length of the four edge portions 1a,
1b of the laminate member 1. The paired projections formed in the
groove of each frame were continuous from one end of said frame to
the other, so that, when the edge portions of four sides of the
laminate member 1 were inserted in the respective frames, said end
portions were continuously pressed over the entire periphery by the
paired projections on said frames. When the four edge portions of
four sides of laminate member 1 are inserted into the grooves of
the frames 6,7, the ends of neighboring frames were mutually fixed
by a screw.
The solar cell module of the present invention was prepared by
inserting the edge portions 1a, 1b of four sides of the laminate
member 1 into the grooves 6a, 7a of the four frames 6, 7, filling
the gap between the edge portions and the grooves with silicone
rubber pottant 6f, 7f, pressing each frame in the portion of the
groove thereof from the light-receiving side and from the rear
side, connecting the ends of neighboring frames with screws,
mounting a waterproof terminal box on a part of the frame at the
side of the rear face protecting material 5, positioning the output
terminals of the solar cell device drawn from an end face of the
laminate member 1 in said terminal box, and leaving thus obtained
module for three days for completely drying said pottant. During
the insertion of said end portions, it was confirmed that the
surface protecting material 4 and the rear face protecting material
5 of the edge portion on each side of the laminate member 1 were
recessed by about 0.2 mm by the pressure of the paired projections
6d, 6e, 7d, 7e. Ten such solar cell modules were prepared in this
manner.
Separately, there were prepared 10 conventional solar cell modules,
which were identical, in structure and manufacturing process, with
the modules of the present invention, except that the groove of
each frame lacked the paired projections.
The ten solar cell modules of the present invention and the ten
conventional modules were placed under a high humidity, in a
commercial weather testing apparatus, having a chamber of
1.5.times.1.0.times.1.0 m and capable of controlling the relative
humidity in said chamber within a range from 0 to 100%
The ten solar cell modules of the present invention and the ten
conventional modules were horizontally positioned, with the surface
protecting material 4 at the top, in said chamber of the weather
testing apparatus, with a mutual spacing of 10 cm. The output
terminals of each solar cell device 2 were left open in the
waterproof terminal box. In such state, the modules were left for
1000 hours at a temperature of 50.degree. C. and a relative
humidity of 85% in said chamber, without light irradiation of the
solar cell devices.
After standing for 1000 hours, each solar cell module was taken out
from the weather testing apparatus, and, after the dew and moisture
on the surface were wiped off with a cloth, the module was
subjected to measurement of electrical performance at room
temperature, employing a commercial artificial solar light
generator, emitting artificial solar light of AM 1.5 global, 1000
mW/cm.sub.2.
In the 10 conventional modules, a reduction of shunt resistance to
1/10 or lower in comparison with that before the high humidity
exposure or a shortcircuiting of the entire module was observed in
6 units. On the other hand, in the 10 modules of the present
invention, a similar shortcircuiting was observed in 1 unit, but
the remaining 9 units were intact. The effect of the paired
projections 6d, 6e, 7d, 7e was proved in this manner.
EXAMPLE 9
In this example, in the grooves 6a, 7a of the frames 6, 7 employed
in the solar cell modules of the present invention, the mutually
opposed projections 6d, 6e, 7d, 7e were formed in intermittent
manner, with each continuous length of 10 cm and a spacing of 10
cm. Other conditions were the same as in the example 8.
In the experimental results, in 10 conventional solar cell modules,
a reduction of shunt resistance of the solar cell device to 1/10 or
lower in comparison with that prior to exposure to high humidity or
a shortcircuiting of the entire solar cell module was observed in 7
units. On the other hand, in 10 modules of the present invention, a
similar reduction of shunt resistance or a shortcircuiting was
observed only in 3 units. Thus the effect of the paired projections
6d, 6e, 7d, 7e was proved even when they were formed
intermittently.
EXAMPLE 10
In this example, the conditions were identical with those in
example 8, except that, in the groove of each frame 16 or 17 shown
in FIG. 14, a projection 16d or 17d is formed continuously only on
the upper internal face 16b or 17b.
In the experimental results, in 10 conventional solar cell modules,
a reduction of shunt resistance of the solar cell device to 1/10 or
lower in comparison with that prior to exposure to high humidity or
a shortcircuiting of the entire solar cell module was observed in 7
units. On the other hand, in 10 modules of the present invention,
such reduction of shunt resistance or shortcircuiting was observed
only in 4 units. Thus the effect of the projection was proved even
when it was formed only on one internal face of the groove of the
frame.
In the above-explained examples 6 to 10, a groove or grooves formed
on the internal faces of the groove of the frame locally presses a
contact area of the edge portion of the laminate member, inserted
into said groove, thereby preventing the intrusion of moisture,
entering said edge portion from the end face thereof, into the
interior beyond said pressed area, and thus improving the
resistance against moisture intrusion into the interior of the
laminate member. As a result, the breakdown of the solar cell
device resulting from such moisture intrusion can also be
prevented.
In the following, there will be explained the method of
installation of the solar cell modules shown in the foregoing
examples 1-10.
The solar cell is usually installed on a rack fixed on the ground
or on the roof of a building, or adhered to the wall of a building.
In the case of installation on the roof, the solar cell may also be
integrated with the roofing material and placed on the roof without
the rack.
As an example of such method, a solar cell device sealed in resin
sheets or EVA is adhered with an adhesive material, to a rear face
metal protecting plate. The end portions of said protecting metal
plate are folded upwards to form sealing portions for said solar
cell, then a plurality of such sealing portions are adhered to the
roof surface, and a batten-seam is placed over the end portions,
parallel to the slanting direction of the roof, for protecting the
seal portions of the solar cells and the end faces of the
protecting metal plates. This method has an advantage of dispensing
with the cost of rack, in comparison with an installation with a
rack on the roof.
The conventional solar cell modules, particularly those in which
the solar cell device is vacuum laminated with surface protecting
materials consisting of sheet-like transparent resin, are usually
trimmed to a predetermined shape by cutting the surface protecting
material, adhesive material, and rear face protecting material at
positions outside the solar cell device. It is therefore necessary
to suitably treat the end portions formed by such cutting, in order
to protect the internally sealed solar cell device and electric
circuits from the stress, water, and moisture (vapor) originating
from the ambient conditions.
If the seal portion of the solar cell is adhered, with an adhesive
material, to a rear face metal protecting plate, the end face of
said seal portion may be treated in the following manner, as the
aforementioned frame is absent in this case.
There was first conceived a method of protecting the end portion by
covering it with an adhesive material or a pottant such as silicone
rubber, prior to the adhesion of the seal portion of the solar cell
to the rear face metal protecting plate. However, the surface
protecting material of said seal portion, enclosing a solar cell
device employing a conductive substrate such as a stainless steel
substrate, is often composed of fluorinated resin or the like, for
which effective adhesives or pottants are not known. The
fluorinated resin is used for such surface protecting material
because of its high light transmittance and high durability to
stress caused by the ambient conditions. The fluorinated resin also
provides low dust deposition and a high water repellant property,
required for the surface protecting material, but this fact also
signifies the absence of a suitable adhesive therefor. Since the
fluorinated resin and EVA cannot be adhered to satisfactorily, the
adhesion if often improved by applying a corona discharge to the
entire adhered surface of the fluorinated resin. However, the
corona discharge, if applied to the entire top surface of the
fluorinated resin, will deteriorate the dust and water repellant
properties mentioned above. Also such corona discharge, if applied
only to the end portion, will require an increased precision of the
sealing operation and increase the process cost.
Another conceivable method consists of heating the end portion,
thereby fusing and expelling the adhesive material, such as EVA,
from the seal portion, and thermally adhering the surface
protecting resin material and the rear face protecting resin
material under pressure, prior to the adhesion of the seal portion
of the solar cell to the rear face metal protecting plate. However,
such thermal adhesion, experimented with by the present inventors
at various temperatures, has not provided sufficient adhesive
strength.
As explained in the foregoing, various difficulties arise in the
treatment of the end portions, in the case where the seal portion
of the solar cell is to be adhered to the rear face metal
protecting plate.
In consideration of the foregoing, another object of the present
invention, different from those of the foregoing examples 1-10, in
a solar cell module which includes plural seal portions of solar
cells, each including a solar cell device and a rear face metal
protecting plate serving as a support member, and a batten-seam
member for protecting vertically positioned ones among the
neighboring end portions of said rear face metal protecting plates
when they are installed on a roof, wherein said seal portions are
integrated with the roofing material, is to prevent the deformation
or destruction of said end portions of the seal portions by
external stress or in intrusion of water vapor from said end
portions to the solar cell device, thereby avoiding failure of the
solar cell device or shortcircuiting or internal wirings caused by
such intruding water vapor.
The above-mentioned object can be achieved, according to the
present invention, by a solar cell module which includes plural
seal portions of solar cells, each including a solar cell device
and a rear face metal protecting plate, and a batten-seam member
for protecting vertically positioned ones among the neighboring end
portions of said rear face protecting metal plates when they are
installed on a roof and in which said seal portions are integrated
with the roofing material, wherein said rear face protecting metal
plate is provided, at the end portions thereof, with slit-shaped
grooves formed by folding said metal plate.
The solar cell module of such structure allows prevention of
deformation or destruction of the end portions of said solar cell
seal portions by external stress and intrusion of water vapor from
said end portions to the solar cell device, thereby avoiding
failure of said device or shortcircuiting or internal wirings
caused by such intruding water vapor.
EXAMPLE 11
FIG. 15 is a schematic cross-sectional view of an amorphous solar
cell module, best representing the feature of the present example.
There are illustrated an amorphous solar cell device 31; a rear
face metal protecting plate 32; an adhesive layer 33; a front
surface protecting material 34; a rear face protecting material 35;
pottant 36; a batten-seam member 37; and a slit-shaped groove 38
formed by folding said metal plate. The solar light h.nu. enters
the module from above. The amorphous solar cell device 31 is
composed, for example, of a serial connection of a plurality of
devices each formed, on a stainless steel substrate, by laminating
amorphous silicon films of N, I, P, N, I, and P types in succession
by RF glow discharge, then evaporating indium tin oxide as a
transparent electrode, and finally printing silver paste as grid
electrodes.
The solar cell module of this example is formed by inserting the
seal portion of the solar cell into the slit-shaped groove 38,
formed by folding the protecting metal plate 32 at the end portion
thereof. In FIG. 15, the wirings and output terminals of the solar
cell device are omitted.
The form and dimension of said slit-shaped groove 38 are preferably
so selected that said groove does not induce deformation nor damage
of the end portion of the seal portion at the insertion thereof or
after a prolonged inserted state and that a suitable pottant 36 can
easily fill the gap between the groove 38 and the end portions. As
an example, the groove 38 is formed deeper, as shown in FIG. 15,
than the inserted length of the end portion thereby leaving a gap
for filling with the pottant, but such configuration is not
limitative.
Also said groove 38 is preferably formed without interruption over
the entire length of the longer and shorter sides of the end
portions of the solar cell seal portions.
The rear face metal protecting plate 32 is preferably composed of a
material whose surface is treated so as to have sufficient
durability required for the roofing material against ambient
conditions and allows easy formation of the slit-shaped groove 38
by folding. An example of such material is galvanized steel plate,
but each example is not limitative.
A non-limitative example of the adhesive layer 33 is EVA. Also, a
non-limitative example of the upper surface protecting material 34
is fluorinated resin. In this example, the sealing is achieved by
vacuum lamination of sheet-shaped fluorinated resin, but the
surface protecting material 34 may also be formed, for example, by
coating a liquid fluorinated resin.
The rear face protecting material 35 is composed of a material
capable of electrically insulating the solar cell device from the
rear face metal protecting plate 32. A non-limitative example of
such material is sheet-shaped nylon.
Non-limitative examples of the pottant 36 are silicone rubber and
butyl rubber.
Sealing is achieved more preferably by forming a projection 38b in
the groove 38, as in the foregoing examples 6-10 (see (A) in FIG.
15B). Also, penetrating holes may be provided in the protecting
materials 34, 35 as in examples 1-5.
In the present example, the solar cell module prepared by vacuum
lamination of the amorphous silicon solar cell device 31 with the
surface protecting material 34, rear face protecting material 35,
and adhesive layer 33 was left in a high humidity condition, and
was subjected to an investigation of frequency of failures such as
peeling of end portions of the solar cell seal portions, and
failure of the solar cell devices and shortcircuiting of the entire
module caused by water vapor intrusion.
The amorphous solar cell 31 employed in the example was prepared,
on a stainless steel substrate, by laminating amorphous silicon
films of N, I, P, N, I, and P types in succession by an RF glow
discharge method, then evaporating indium tin oxide as the
transparent electrode, and printing silver paste as a
current-collecting grid electrode, and 13 such cells, each ca.
30.times.9 cm, were connected serially.
The adhesive layer 33 consisted of sheet-shaped EVA, while the
front surface protecting material 34 consisted of sheet-shaped
Tefzel of a thickness of 100 .mu.m, and the rear face protecting
material 35 consisted of a sheet in which an aluminum foil was
sandwiched between white Tedlar sheets.
The above-mentioned materials were superposed in succession, from
the bottom, in the order of the rear face protecting material 35,
adhesive layer 33, amorphous silicon solar cell device 31, adhesive
layer 32, and front surface protecting material 34, and were
laminated at 100.degree. C. in a vacuum laminator. The obtained
laminate member was cut into a rectangular form at positions of the
solar cell seal portions, and failure of the solar cell devices and
shortcircuiting of the entire module caused by water vapor
intrusion.
The amorphous solar cell 31 employed on this example was prepared,
on a stainless steel substrate, by laminating amorphous silicon
films of N, I, P, N, I, and P types in succession by an RF glow
discharge method, then evaporating indium tim oxide as the
transparent electrode, and printing silver paste as a current
collecting grid electrode, and 13 such cells, each ca. 30.times.9
cm, were connected serially.
The adhesive layer 33 consisted of sheet-shaped EVA, while the
front surface protecting material 34 consisted of sheet-shaped
Tefzel of a thickness of 100 .mu.m, and the rear face protecting
material 35 consisted of a sheet in which an aluminum foil was
sandwiched between white Tedlar sheets.
The above-mentioned materials were superposed in succession, from
the bottom, in the order of the rear face protecting material 35,
adhesive layer 33, amorphous silicon solar cell device 31, adhesive
layer 33, and front surface protecting material 34, and were
laminated at 100.degree. C. in a vacuum laminator. The obtained
laminate member was cut into rectangular form at positions 2 cm
outside the external periphery of the solar cell device. The cut
faces were not particularly treated.
The rear face metal protecting plate 32, consisting of a galvanized
steel plate of a thickness of ca. 0.3 mm and having a weather
resistant treatment on one side thereof, was cut into a size of
1.5.times.0.45 m and folded in the following manner. At first the
mutually opposed longer sides of the steel plate were folded over
the entire width to form slit-shaped grooves 38 of a width of ca. 4
mm and a depth of 1 cm, as shown in FIG. 15A. Then, each end
portion of about 4 cm was folded upwards, and finally each end
portion of about 1 cm was folded diagonally downwards. FIG. 16 is a
schematic perspective view showing the thus folded metal plate 32,
and FIG. 17 is a schematic perspective view showing a state in
which the seal portions of the solar cell were inserted, on a trial
basis, into said rear face metal protecting plate 32. Then the
mutually opposed shorter sides were similarly folded to form
slit-shaped grooves 40 of a width of ca. 4 mm and a depth of ca. 1
cm. During said folding operation, in order to avoid interference
with the end portions of the already folded longer sides, slits
were made in advance in the portions of the shorter sides to be
folded. FIG. 18 is a schematic perspective view of the completed
state of the rear face protecting metal plate 32.
Separately, as a conventional example, a rear face protecting metal
plate without the slit-shaped groove 38 was prepared with a steel
plate the same as explained above, having a size of ca.
1.5.times.0.39 m. More specifically, the end portions of said steel
plate were at first folded upwards for a length of ca. 4 cm, then
folded diagonally downwards for a length of ca. 1 cm.
The batten-seam member 37 was formed, with a galvanized steel plate
of a thickness of ca. 0.3 mm, similar to the rear face protecting
metal plate 32, by folding so as to obtain a square U-shape cross
section in which the ends were further folded back, as shown in
FIG. 15. The square U-shape had a length of ca. 4 cm on each side,
and the folded end portions had a length of ca. 1 cm.
After silicone rubber pottant is filled in the slit-shaped grooves
38, 40 of the metal plate 32, epoxy adhesive was coated on the rear
face of the seal portions of the solar cell obtained by laminating
the amorphous solar cell device 31 as explained above, then the
edge portions of longer and shorter sides of said seal portions
were inserted into said grooves 38, 40 and the light-receiving
surface of the solar cell was pressed. Finally, the output
terminals (not shown) were mounted on the seal portion, and a
waterproof terminal box, for protecting said terminals, was mounted
on the rear side of the module. The obtained module was then let to
stand for 3 days until the filler 36 and the adhesive completely
solidified. Two units thus prepared, each including the solar cell
seal portions and the rear face protecting metal plate 32, were
installed with a mutual spacing of ca. 3 cm between the longer
sides, on a wooden sheet of a size of 1.5.times.0.8 m and a
thickness of 2 cm, simulating a roof covering 39, and said spacing
was covered by the batten-seam member prepared in advance, whereby
the solar cell module of the present invention was completed. Ten
modules were prepared in this manner.
Also, as a conventional example, aqueous adhesive was coated on the
rear face of the seal portions of a solar cell, obtained by
laminating a similar amorphous solar cell device, and said solar
cell was adhered to a rear face protecting metal plate without the
slit-shaped grooves 38, 40. Output terminals were mounted on the
seal portion, and a water-proof terminal box was mounted on the
rear side of the module. Two units thus prepare were installed with
a mutual spacing of ca. 3 cm between the longer sides, on a wooden
sheet of a size of 1.5.times.0.8 m and a thickness of 2 cm,
simulating a roof covering 39, and said spacing was covered by the
batten-seam member prepared in advance, whereby the solar cell
module of the conventional example was completed. Ten modules were
prepared in this manner.
The above-explained solar cell modules of two kinds were subjected
to a comparative test for investigating the frequency of peeling of
end portions of the seal or the failure of the solar cell module
resulting from water vapor intrusion from the end portions. The
above-explained 10 solar cell modules were placed under a high
humidity condition in a commercial weather testing apparatus, and
the rate of failure was investigated. Said weather testing
apparatus had a chamber of 1.5.times.1.0.times.1.0 m, and was
capable of controlling the relatively humidity in said chamber
within a range of 0-100%. In order to reproduce the state of
outdoor use of the solar cell module, the temperature in the
chamber was fixed at about 50.degree. C.
In order to reproduce the actual state of outdoor use of the solar
cell module, it is necessary to irradiate the module with light.
However, as already well known, the amorphous silicon solar cell
incurs so-called photodeterioration, so that the electrical
performance of the solar cell module is deteriorated by the light
irradiation. In this experiment, in order to separate the influence
of said photodeterioration of the module from that due to water
vapor intrusion which is important in the present invention, no
light irradiation of the solar cell modules in said chamber was
conducted. Also the output terminals were left open and maintained
in the waterproof terminal box.
The 10 solar cell modules each of the two kinds were horizontally
placed, with the light-receiving face upwards, in said chamber of
the weather testing apparatus, with a mutual spacing of 10 cm, and
left to continuously stand for 1000 hours under a temperature of
50.degree. C. and a relative humidity of 85%.
After 1000 hours, the modules were taken from the apparatus, and,
after wiping off the dew and moisture with a cloth, subjected to
measurement of the electrical performance, employing a commercial
large artificial solar light generator. The artificial solar light
was AM 1.5 global, 100 mW/cm.sup.2, and the measurement was
conducted at room temperature.
In the 10 solar cell modules lacking slit-shaped grooves 38, 40,
peeling of the end portions of the seal, reduction of shunt
resistance to 1/10 or less in comparison with the state prior to
the testing, or a shortcircuiting was observed in 5 modules. On the
other hand, in the 10 solar cell modules with the slit-shaped
grooves 38, 40, similar phenomena were observed only in one module.
These results proved the effect of slit-shaped grooves 38, 40 in
the rear face metal protecting plate.
EXAMPLE 12
In this example, an experiment was conducted to confirm the effect,
when the slit-shaped groove 48 on the rear face metal protecting
plate had a folded structure as shown in FIG. 19. In this
configuration, the vertical end portion of said metal plate is
positioned at the external end of the slit-shaped groove 58, so
that the distance of neighboring metal plates can be reduced at the
module installation and the width of the batten-seam member can
also be reduced. Consequently, the shadow cast by the batten-seam
member onto the light-receiving face of the solar cell device is
reduced, and, as a result, an increase in the total output of the
solar cell module can be expected.
Also in this example, the rear face metal protecting plate 52 was
formed with a galvanized steel plate of a thickness of ca. 0.3 mm,
having a weather resistant treatment on one side thereof and having
a size of 1.5 .times.0.45 m, by folding in the following manner. At
first, both ends of the mutually opposed longer sides of said
rectangular steel plate were folded over the entire width to form
slit-shaped grooves 58 of a width of ca. 4 mm and a depth of 1 cm
as shown in FIG. 19. Then each end portion of the steel plate was
folded upwards, and further folded back so as to contact the
outside of said slit-shaped groove. Then, about 5 mm from said
folded-back portion, said end portion was folded upwards for a
distance of ca. 3 cm, and finally folded diagonally downwards for a
distance of ca. 1 cm. Also, the mutually opposed shorter sides were
folded, in the end portions, as in the example 11, thereby forming
slit-shaped second grooves of a thickness of ca. 4 mm and a depth
of ca. 1 cm. During said folding operation, slits were made in
advance in the folded portions of the shorter sides, in order to
avoid interference with the already folded upward portions of the
ends of the longer sides.
The above-described folded structure permits a reduction of the
distance of the neighboring metal plates 52 at the module
installation, thereby reducing the width of the batten-seam member.
Consequently the shadow cast by the batten-seam member onto the
light-receiving face of the solar call device is reduced, whereby
an increase in the total output of the solar cell module can be
expected.
The method of preparation and the materials for the solar cell
device of the present example are identical with those in the
example 11. Also the method of serial connection of the devices,
the materials and dimensions of the front surface protecting
material 54, rear face protecting material 55 and adhesive layer
53, and the method and conditions of lamination are the same as
those in the example 1. Furthermore, as in example 1, the cut faces
of the laminate member were not treated.
The rear face metal protecting plate 52 of the present example was
prepared by the above-explained procedure, with a steel plate the
same as employed in example 11.
Also, a rear face metal protecting plate of conventional type was
prepared with the same material and dimensions as in example
11.
After silicone rubber pottant was filled into the slit-shaped
grooves 58 and the second grooves (not shown), epoxy adhesive was
coated on the rear face of the seal portions of the thus prepared
amorphous solar cell in the same manner as in example 11, the edge
portions of the longer and shorter sides of said seal portions were
inserted into the slit-shaped grooves mentioned above, and the
solar cell was simultaneously pressed from the light-receiving face
thereof. Finally, output terminals were mounted on the seal
portion, and a waterproof terminal box, for protecting said
terminals, was mounted on the rear side of the module. The obtained
structure was left to stand for 3 days until the pottant 53 and the
adhesive were completely solidified. Two units thus prepared, each
including the solar cell seal portions and the rear face protecting
metal plate 52, were installed with a mutual spacing of ca. 3 cm
between the longer sides, on a wooden sheet of a size of
1.5.times.0.8 m and a thickness of 2 cm, simulating a roof covering
and said spacing was covered by the batten-seam member prepared in
advance, whereby the solar cell module of the present invention was
completed. Ten modules were prepared in this manner.
Also, as a conventional example, epoxy adhesive was coated on the
rear face of seal portions of the solar cell, formed by laminating
a similarly prepared solar cell device, and said solar cell was
adhered on a rear face metal protecting plate without the grooves.
Output terminals were mounted on the seal portion, and a protecting
waterproof terminal box was mounted on the rear side of the module.
Two units thus prepared, each including the solar cell seal
portions and the rear face protecting metal plate, were installed
with a mutual spacing of ca. 3 cm between the longer sides, on a
wooden sheet of a size of 1.5.times.0.8 m and a thickness of 2 cm,
simulating a roof covering and said spacing was covered by a
batten-seam member prepared in advance, whereby the solar cell
module of the conventional type was completed. Ten modules were
prepared in this manner.
The 10 modules of each of the above-described two kinds were
prepared, and subjected to a comparative test for confirming the
effect of the present example, in the same apparatus and procedure
as in example 1.
In the measurement of electrical performance after 1000 hours, in
the 10 modules lacking the slit-shaped grooves 58 and the second
slit-shaped grooves (not shown), peeling in the end portion,
decrease of shunt resistance to 1/10 or lower in comparison with
the state prior to testing, or shortcircuiting was observed in 4
modules. On the other hand, in the 10 modules provided with the
slit-shaped grooves, similar phenomena were not observed. Thus,
also in this example, the effect of slit-shaped grooves 58 and the
second slit-shaped grooves (not shown) was proved.
EXAMPLE 13
In this example, as experiment was conducted to confirm the effect,
when the slit-shaped groove 68 on the rear face metal protecting
metal plate had a folded structure as shown in FIG. 20. This
example provides the advantage that the folding work for forming
said grooves 68 is simpler than in the examples 11 and 12.
Also in this example, the rear face metal protecting plate 62 was
formed from a galvanized steel plate of a thickness of ca. 0.3 mm,
having a weather resistant treatment on one side thereof and a size
of 1.5.times.0.45 m, by folding in the following manner. At first,
each end of the mutually opposed longer sides of said rectangular
steel plate was folded downwards over the entire width, for a
length of ca. 1 cm from the end. Then the steel plate was folded
upwards at a position of ca. 3.6 cm from the above-mentioned fold
and further folded by 180.degree.. Then the plate was folded
upwards at a position of ca. 4 cm from side 180.degree. folded
position, thereby forming a slit-shaped groove 68 of a thickness of
ca. 4 mm and a depth of 1 cm. Also, the end portions of the
mutually opposed shorter sides were folded as in the example 11 to
form second grooves (not shown) of a thickness of ca. 4 mm and a
depth of ca. 1 cm.
The method of preparation and the materials of the amorphous solar
cell device, and the method, materials, and conditions of
lamination were the same as those in example 11. Ten units each of
the solar cell modules with the slit-shaped grooves 68 and the
second slit-shaped grooves (not shown), and the conventional
modules without said grooves were thus prepared. In the present
example, however, a fastening member 71 of the cross section shown
in FIG. 20 was employed for fastening the batten-seam member.
These modules were subjected to a comparative test for confirming
the effect of the present example, with the same apparatus and
procedure as in examples 11 and 12.
In the measurement of electrical performance of each module after
1000 hours, in the 10 modules lacking said slit-shaped grooves,
peeling of the end portion of the seal portion, reduction of shunt
resistance to 1/10 or lower in comparison with the state prior to
testing or shortcircuiting was observed in 4 modules. On the other
hand, in 10 modules with the slit-shaped grooves 68 and the second
slit-shaped grooves, such phenomena were observed only in one
module. Thus, also in this example, the effect of the slit-shaped
grooves 68 and the second slit-shaped grooves was confirmed.
As explained in the foregoing, in a solar cell module which
includes plural seal portions of solar cells, each including a
solar cell device and a rear face metal protecting plate, and a
batten-seam member for protecting vertically positioned ones among
the neighboring end portions of said rear face metal protecting
plates when they are installed on the roof and in which said seal
portions are integrated with the roofing material, slit-shaped
grooves are provided at the end portions of said rear face
protecting metal plate by folding said metal plate, thereby
preventing the peeling or damage of the end portions of the solar
cell seal portions and also preventing water vapor intrusion to the
seal portions, whereby breakdown of the solar cell device and
shortcircuiting of internal wirings, resulting from such water
vapor intrusion can be avoided.
The following examples, relating to a solar cell module which
includes plural seal portions of solar cells, each including a
solar cell device and a rear face protecting metal plate serving as
a support member, and a batten-seam member for protecting
vertically positioned ones among the neighboring end portions of
said rear face protecting metal plates when they are installed on
the roof and in which said seal portions are integrated with the
roofing material, prevent deformation or damage of the end portions
of the solar cell seal portions by external stress and prevent
water vapor intrusion from said end portions of the solar cell
device, thereby avoiding failure of the solar cell device or
shortcircuit of internal wirings resulting from such water vapor
intrusion.
In the following examples there are provided such solar cell
modules as explained above, which are characterized by that, at the
end portions of said rear face protecting metal plate, slit-shaped
grooves are formed by said metal plate and separate members. In the
solar cell module of the above-mentioned configuration, said
slit-shaped grooves protect, in cooperation with pottant material,
the end portions of the solar cell seal portions, thus preventing
peeling or damage of said end portions and water vapor intrusion
from said end portions to the solar cell device, thereby avoiding
failure of solar cell device and shortcircuiting of internal
wirings resulting from such water vapor intrusion.
EXAMPLE 14
FIGS. 21A and 21B show schematic cross sectional views of an
amorphous solar cell module and best represents the feature of the
present example. There are shown an amorphous solar cell device 31;
a rear face metal protecting plate 32; an adhesive layer 33; a
front surface protecting material 34; a rear face protecting
material 35; a pottant 36; a batten-seam member 37; slit-shaped
grooves 38; and groove-forming members 43. The solar light h.nu.
enters from above. The solar cell device 31 is composed, for
example, of a serial connection of devices each formed, on a
stainless steel substrate, by laminating amorphous silicon films of
N, I, P, N, I, and P types in succession by RF glow discharge, then
evaporating indium tin oxide as a transparent electrode, and
finally printing silver paste as a grid electrode.
The solar cell module of this example is formed by inserting the
seal portions of the solar cell in the slit-shaped grooves 38,
formed at the end portions of the rear face metal protecting plate
32 by means of said plate 32 and groove forming members 43. In FIG.
21A, the wirings and output terminals of the solar cell device are
omitted.
The form and dimension of said slit-shaped groove 38 are preferably
so selected that said groove does not induce deformation nor damage
on the end portion of the seal portion during the insertion thereof
or after a prolonged inserted state and that suitable pottant 36
can be easily filled into the gap between the groove 38 and the end
portion. As an example, the groove 38 is formed deeper, as shown in
FIG. 21A, than the inserted length of the end portion, thereby
leaving a gap for filling with the pottant, but such configuration
is not limitative.
Also, said groove 38 is preferably formed without interruption over
the entire length of the longer and shorter sides of the end
portions of the solar cell seal portions.
The rear face metal protecting plate 32 and the groove forming
member 43 are preferably composed of a material which is surface
treated so as to have sufficient durability required for the
roofing material against ambient conditions and permits easy
folding. An example of such material is galvanized steel plate, but
such example is not limitative.
A non-limitative example of the adhesive layer 33 is EVA. Also, a
non-limitative example of the front surface protecting material 34
is fluorinated resin. In this example, the sealing is achieved by
vacuum lamination of sheet-shaped fluorinated resin, but the
surface protecting material 34 may also be formed, for example, by
coating liquid fluorinated resin.
The rear face protecting material 35 is composed of a material
capable of electrically insulating the solar cell device from the
rear face metal protecting plate 32. A non-limitative example of
such material is sheet-like nylon.
Non-limitative examples of the filler 36 are silicon rubber and
butyl rubber.
Also, the groove forming member 43 may be provided with a
projection engaging with a recess in the materials 34, 35 as shown
in FIG. 15, or with a projection 43a inserted into a penetrating
hole formed in said material 34, 35 as shown in FIG. 21(B). In this
manner excellent effects can be obtained by combinations with the
examples 1-10.
In the present example, the solar cell module prepared by vacuum
lamination of the amorphous silicon solar cell device 31 with the
front surface protecting material 34, rear face protecting material
35, and adhesive layer 33 was left in high humidity conditions, and
was subjected to the investigation of frequency of failures such as
peeling of end portions of the solar cell seal portions, failure of
the solar cell device, and shortcircuiting of entire module caused
by water vapor intrusion.
The amorphous solar cell 31 employed in this example was prepared,
on a stainless steel substrate, by laminating amorphous silicon
films of N, I, P, N, I, and P types in succession by an RF glow
discharge method, then evaporating indium tin oxide as the
transparent electrode, and printing silver paste as current
collecting grid electrode. 13 units of such cell, each ca.
30.times.9 cm, were serially connected.
The adhesive layer 33 consisted of sheet-like EVA, while the
surface protecting material 34 consisted of sheet-like Tefzel
(DuPont) of a thickness of 100 .mu.m, and the rear face protecting
material 5 consisted of a sheet in which an aluminum foil was
sandwiched between while Tedlar (DuPont) sheets.
The above-mentioned materials were superposed in succession, from
the bottom, in order of the rear face protecting material 35,
adhesive layer 33, amorphous silicon solar cell device 31, adhesive
layer 33, and front surface protecting material 34, and were
laminated at 100.degree. C. in a vacuum laminator. The obtained
laminate member was cut into a rectangular form at positions 2 cm
outside the external periphery of the solar cell device. The cut
faces were not particularly treated.
The rear face protecting metal plate 32, consisting of a galvanized
steel plate of a thickness of ca. 0.3 mm and having a weather
resistant treatment on one side thereof, was cut into a size of
1.5.times.0.45 m and folded in the following manner. Each end
portion of the mutually opposed longer side of said rectangular
steel plate was at first folded upward for a length of ca. 4 cm,
and then the portion was folded diagonally downwards for a length
of ca. 1 cm. 10 pieces of such steeply folded plate were
prepared.
The groove forming member 43, consisting of a galvanized steel
plate of thickness of ca. 0.3 mm and having a weather resistant
treatment on one side thereof, was cut into a size of 1.5
m..times.3 cm and folded over the entire length in such a manner
that the cross section of the shorter side assumes an L-form with
sides of 1 and 2 cm. 20 pieces of such member were prepared. Then
said groove forming members 43 were adhered, with an adhesive
material, to the rear face metal protecting plate 32, thereby
forming, as shown in FIG. 21A, slit-shaped grooves 38 of a
thickness of ca. 4 mm and a depth of ca. 10 mm, on the upward
folded portions of the longer sides of the metal plate 32. In this
example, the groove forming members 43 were adhered by an adhesive
material to the metal plate 32, but the adhesion may also be
achieved by welding or soldering, or by the use of a junction
member such as a grommet. FIG. 22 is a schematic perspective view
of the groove forming members 43 and the rear face protecting metal
plate 32 combined as explained above, and FIG. 23 is a schematic
perspective view showing a state in which the seal portions of the
solar cell were experimentally inserted into said slit-shaped
grooves 38 formed in said metal plate 32. On the other hand, for
the end portions of the mutually opposed short sides, groove
forming members 44 were prepared by folding a galvanized steel
plate of a thickness of 0.3 mm, having a weather resistance
treatment on one side and having a size of ca. 0.32.times.0.02 m,
over the entire length of 0.32 m so as to have an L-shaped cross
section of 1.times.1 cm on the shorter side. Said members were
adhered, with an adhesive material, to the metal plate 32 and the
groove forming members 43 thereby forming slit-shaped grooves (not
shown) of a thickness of ca. 4 mm and a depth of ca. 10 mm also on
the ends of the shorter sides. FIG. 24 is a schematic perspective
view showing the completed state of the rear face protecting metal
plate 32 and the groove forming members 43, 44.
Separately, as a conventional example, the rear face protecting
metal plate 32 without the slit-shaped grooves was prepared in the
following manner, by folding a galvanized steel plate of a
thickness of ca. 0.3 mm, having a weather resistant treatment on
one side and having a size of 1.5.times.0.45 m. Each end of the
mutually opposed longer sides of said rectangular steel plate was
folded, over the entire width, upwards for a length of ca. 4 cm,
and then the end portion was folded diagonally downwards for a
length of ca. 1 cm. 10 units were prepared in this manner.
The batten-seam member 37 was formed, with a galvanized steel plate
of a thickness of ca. 0.3 mm, similar to the rear face protecting
metal plate 32, by folding so as to obtain a square U shaped cross
section of which the ends were further folded back, as shown in
FIG. 21. The square U-shape had a length of ca. 4 cm on each side,
and the folded end portions had a length of ca. 1 cm.
After silicone rubber pottant was filled in the slit-shaped grooves
at the ends of the metal plate 32, epoxy adhesive was coated on the
rear face of the seal portions of the solar cell prepared as
explained above, then the edge portions of longer and shorter sides
of said seal portions were inserted into said grooves and the
light-receiving face of the solar cell was pressed. Finally, output
terminals (not shown) were mounted on the seal portion, and a
waterproof terminal box, for protecting said terminals, was mounted
on the rear side of the module. The obtained structure was then
left to stand for 3 days until the pottant and the adhesive were
completely solidified. Two units thus prepared, each including the
solar cell seal portions and the rear face protecting metal plate
32, were installed with a mutual spacing of ca. 3 cm between the
longer sides, on a wooden sheet of a size of 1.5.times.0.8 m and a
thickness of 2 cm, simulating a roof covering 39, and said spacing
was covered by the batten-seam member prepared in advance, whereby
the solar cell module of the present invention was completed. 10
modules were prepared in this manner.
Also as a conventional example, epoxy adhesive was coated on the
rear face of the seal portions of a solar cell, obtained by
laminating a similar amorphous solar cell device, and said solar
cell was adhered to a rear face metal protecting plate without the
slit-shaped grooves. Output terminals were mounted on the seal
portion, and a water-proof terminal box was mounted on the rear
side of the module. Two units thus prepared were installed with a
mutual spacing of ca. 3 cm between the longer sides, on a wooden
sheet of a size of 1.5.times.0.8 m and a thickness of 2 cm,
simulating a roof covering 39, and said spacing was covered by the
batten-seam member prepared in advance, whereby the solar cell
module of the conventional example was completed. 10 modules were
prepared in this manner.
The above-explained solar cell modules of two kinds were subjected
to a comparative test for investigating the frequency of peeling of
end portions of the seal and failure of the solar cell module
resulting from water vapor intrusion from the end portions. The
above-explained solar cell modules were placed under a high
humidity condition in a commercial weather testing apparatus, and
the rate of failure was investigated. Said weather testing
apparatus had a chamber of 1.5.times.1.0.times.1.0 m, and was
capable of controlling the relative humidity in said chamber within
a range of 0-100%. In order to reproduce the state of outdoor use
of the solar cell module, the temperature in the chamber was fixed
at about 50.degree. C.
In order to reproduce the actual state of outdoor use of the solar
cell module, it is necessary to irradiate the module with light.
However, as is well known, the amorphous silicon solar cell
experience so-called photodeterioration, whereby the electrical
performance of the solar cell module is deteriorate by light
irradiation. In this experiment, in order to separate the influence
of said photodeterioration to the module from that of water vapor
intrusion which is important in the present invention, light
irradiation of the solar cell modules in said chamber was not
conducted. Also, the output terminals were left open and maintained
in the waterproof terminal box.
The solar cell modules of two kinds were horizontally placed, with
the light receiving face upwards, in said chamber of the weather
testing apparatus, with a mutual spacing of 10 cm, and left to
continuously stand for 1000 hours under a temperature of 50.degree.
C. and a relative humidity of 85%.
After 1000 hours, the modules were taken out from the apparatus,
and, after wiping of the dew and moisture with a cloth, subjected
to the measurement of electrical performance, employing a
commercial large artificial solar light generator. The artificial
solar light was AM 1.5 global, 100 mW/cm.sup.2, and the measurement
was conducted at room temperature.
In 10 solar cell modules lacking slit-shaped grooves, peeling of
the end portions of the seal, reduction of shunt resistance to 1/10
or less in comparison with the state prior to the testing, or
shortcircuiting was observed in 6 modules. On the other hand, in 10
solar cell modules with two pairs of slit-shaped grooves, such
phenomena were not observed. Thus the effect of slit-shaped grooves
provided on the rear face metal protecting plate was confirmed.
EXAMPLE 15
In this example, an experiment was conducted to confirm the effect,
when the slit-shaped grooves 58 on the rear face protecting metal
plate had a folded structure as shown in FIG. 25. In this example,
the portion supporting and fixing the batten-seam member was formed
by folding an end portion of a groove forming member 73, instead of
an end portion of the rear face metal protecting metal 52 as in the
example 14. Such configuration provides an advantage of improving
the operational efficiency and reducing the cost, since said
folding operation of the supporting portion can be conducted on a
relatively small groove forming member 73.
Also in this example, the rear face metal protecting plate 52 was
formed with a galvanized steel plate of a thickness of ca. 0.3 mm,
having a weather resistant treatment on one side thereof and a size
of 1.5.times.0.45 m, by folding in the following manner. Each end
of the mutually opposed longer sides of said rectangular steel
plate was folded upwards for a length of ca. 4 cm, as shown in FIG.
21A. 10 units were prepared in this manner.
The groove forming member 73 was formed of a galvanized steel plate
of a thickness of ca. 0.3 mm, having a weather resistant treatment
on one side thereof and a size of 1.5 m.times.6 cm, by diagonally
folding an end portion with a width of 1 cm over the entire length
of 1.5 m, and further folding said plate over the entire length of
1.5 m so as to obtain an L-shaped cross section with sides of 1 and
2 cm. Said groove forming members 73 were prepared in 20 units.
Then said groove forming member 73 was adhered, with an adhesive
material, to the side of each upward folded portion at the end of
the metal plate 52, so as to form a slit-shaped groove 58 on said
upward folded portion, as shown in FIG. 25. The method of adhesion,
conducted with an adhesive material in this example, may also be
conducted by welding or soldering, or with a fastener member such
as a grommet.
Also, for the ends of the mutually opposed shorter sides, groove
forming members (not shown) were prepared by employing a galvanized
steel plate of a thickness of ca. 0.3 mm, having a weather
resistant treatment on one side thereof and a size of ca.
0.32.times.0.02 m, by folding over the entire length of 0.32 m so
as to obtain an L-shaped cross section with sides of 1 and 1 cm.
Said member was adhered, with an adhesive material, to an end of
the rear face metal protecting plate 52 and the groove forming
members 73, so as to form a slit-shaped groove of a thickness of
ca. 4 mm and a depth of ca. 10 mm also at the end of the shorter
side.
Separately, as a conventional example, a rear face metal protecting
plate without the slit-shaped grooves, as in the example 14, was
prepared in the following manner, with a galvanized steel plate of
a thickness of ca. 03. mm, having a weather resistant treatment on
one side and a size of 1.5.times.0.45 m. Each end of the mutually
opposed longer sides of said rectangular steel plate was folded,
over the entire width, upwards for a length of ca. 4 cm, and then
the end portion was folded diagonally downwards for a length of ca.
1 cm, as shown in FIG. 25. 10 units were prepared in this
manner.
The method of preparation and materials for the solar cell device
of the present example are identical with those in the example 14.
Also, the method of serial connection of the devices, the materials
and dimensions of the surface protecting material 54, rear face
protecting material 55 and adhesive layer 53, and the method and
conditions of lamination are the same as those in the example 14.
Furthermore, as in the example 14, the cut faces of the laminate
member were not treated.
After silicone rubber pottant was filled into the slit-shaped
grooves 58 and second grooves (not shown), epoxy adhesive was
coated on the rear face of the seal portions of the thus prepared
amorphous solar cell in the same manner as in the example 14, then
the edge portions of longer and shorter sides of said seal portions
were inserted into the slit-shaped grooves mentioned above, and the
solar cell was at the same time pressed from the light-receiving
face thereof. Finally, output terminals were mounted on the seal
portion, and a waterproof terminal box, for protecting said
terminals, was mounted on the rear side of the module. The obtained
structure was left to stand for 3 days until the pottant 56 and the
adhesive were completely solidified. Two units thus prepared, each
including the solar cell seal portions and rear face metal
protecting metal 52, were installed with a mutual spacing of ca. 3
cm between the longer sides, on a wood sheet of a size of
1.5.times.0.8 m and a thickness of 2 cm, simulating a roof
covering, and said spacing was covered by the batten-seam member
prepared in advance, whereby the solar cell module of the present
invention was completed. 10 modules were prepared in this
manner.
Also as a conventional example, epoxy adhesive was coated on the
rear face of seal portions of the solar cell, formed by laminating
a similarly prepared solar cell device, and said solar cell was
adhered on a rear face metal protecting plate without the grooves.
Output terminals were mounted on the seal portion, and a protecting
water proof terminal box was mounted on the rear side of the
module. Two units thus prepared, each including the solar cell seal
portions and the rear face protecting metal plate, were installed
with a mutual spacing of ca. 3 cm between the longer sides, on a
wooden sheet of a size of 1.5.times.0.8 m and a thickness of 2 cm,
simulating a roof covering, and said spacing was covered by the
batten-seam member prepared in advance, whereby the solar cell
module of the conventional type was completed. 10 modules were
prepared in this manner.
10 modules each of the above-explained two kinds were prepared, and
subjected to a comparative test for confirming the effect of the
present example, in same apparatus and procedure as in the example
14.
In the measurement of electrical performance after 1000 hours, in
the 10 modules lacking the slit-shaped grooves, peeling in the end
portions decrease of shunt resistance to 1/10 or less in comparison
with the state prior to testing, or shortcircuiting was observed in
5 modules. On the other hand, in the 10 modules provided with
slit-shaped grooves, similar phenomena were not observed. Thus,
also in this example, the effect of slit-shaped grooves was
proved.
EXAMPLE 16
In this example, an experiment was conducted to confirm the effect,
when the slit-shaped grooves 83 on the ends of the longer sides of
the rear face protecting metal plate 62 had a folded structure as
shown in FIG. 26. Said metal plate 62 of this example was
rectangularly folded upwards at the end portions as in the example
15, and groove forming members 83 were so placed to cap said upward
end portions. This configuration provides an advantage that the
adhesion of the groove forming member 83 to the upward end portions
of the metal plate 62 can be facilitated. For example, when said
adhesion is achieved with an adhesive material, the thickness of
the slit-shaped groove 68 is easier to define, and particular
fixing members are not required for the members to be adhered,
during the hardening of the adhesive material. Also in the case of
adhesion with a grommet, the operation of pinching the members to
be adhered can be facilitated. In the following there will be
explained the procedure of preparation of the solar cell module of
the present example.
Also in this example, the rear face protecting metal plate 62 was
prepared with a galvanized steel plate of a thickness of ca. 0.3
mm, having a weather resistant treatment on one face thereof and a
size of 1.5.times.0.40 m, by folding the both ends of the mutually
opposed longer sides, over the entire width, upwards by a length of
ca. 3 cm from the ends.
The groove forming member 83 was prepared from a galvanized steel
plate of a thickness of ca. 0.3 mm, having a weather resistant
treatment on one face thereof and a size of 1.5.times.0.06 m by
rectangularly folding at a position of 1 cm from the end and over
the entire length of 1.5 m, and further folding over 180.degree. at
a position of ca. 2.6 cm from the position of above-mentioned
folding. Inside said 180.degree. folded portion, there was formed a
gap of ca. 0.5 mm so as to accommodate the upward folded portion of
the metal plate 62. 20 units of said groove forming members 83 were
prepared. Then an adhesive material was coated on the upward folded
portions of the metal plate 62 and the groove forming members 83
were adhered thereto from above, thereby forming slit-shaped
grooves 68 of a thickness of ca. 4 mm and a depth of ca. 10 mm, as
shown in FIG. 26. Also in this example, the adhesion between the
metal plate 62 and the groove forming members 83 was achieved with
an adhesive material, but said adhesion may also be performed by
welding or soldering, or with a junction member such as a grommet.
FIG. 26 is a schematic cross-sectional view, showing a state in
which the solar cell seal portions are inserted in the groove
forming members 83 and the rear face protecting metal plate 62
combined in the above-explained procedure.
On the other hand, the end portions of the mutually opposed shorter
sides were folded as in the example 15 thereby forming slit-shaped
grooves with a thickness of ca. 4 mm and a depth of ca. 1 cm.
The method of preparation and the materials of the amorphous solar
cell device, and the method, materials, and conditions of
lamination were identical with those in the example 15. 10 units
each of the modules with the slit-shaped grooves and the
conventional modules without such grooves were prepared. In the
present example, a mounting member 67, 82 of a cross section shown
in FIG. 26 was employed for mounting the batten-seam member.
These modules were subjected to a comparative test for confirming
the effect of the present example, employing the same apparatus as
in examples 1 and 2.
In the measurement of electrical performance after 1000 hours, in
the 10 modules without the slit-shaped grooves, peeling of the end
portion in the solar cell seal portions, reduction of shunt
resistance to 1/10 or lower in comparison with the state prior to
testing, or shortcircuiting was observed in 4 modules. On the other
hand, in the 10 modules with the slit-shaped grooves, such
phenomena were not observed. Thus, also in this example, the effect
of the slit-shaped grooves was confirmed.
As explained in the foregoing, in a solar cell module which
includes plural seal portions, a rear face metal protecting plate
serving as a support member, and a batten-seam member for
protecting vertically positioned ones among the neighboring end
portions of said rear face metal protecting plates when they are
installed on a roof and in which said seal portions are integrated
with the roofing material, slit-shaped grooves are provided at the
ends of said metal plate, said grooves being formed by means of
said metal plate and independent members, thereby preventing the
peeling or damage of end portions of said seal portions of the
solar cells and also preventing the intrusion of water vapor from
said end portions to the solar cell device, whereby the failure of
solar cell device and shortcircuit of the internal wirings of the
solar cell module can be avoided.
FIG. 28 is a schematic view showing the final form of the solar
cell modules of the present invention, wherein there are shown
solar cells 2001 each including a photovoltaic device covered with
covering materials; a support member 2003 therefor, provided at the
ends of the solar cells 2001; and protective member for each two
neighboring solar cells. These members are constructed as explained
in the examples 1-16.
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